We would infect each other with little disruption to our lives and the economy. Before long, the virus would have run its course ... with no one else to infect.
Unfortunately, our system does not have the capacity to treat the 10% who become seriously ill and require medical care.
There will be more pandemics in the future. Obviously, getting way out in front of it, and shutting down movement in the country on the very front end would flatten the curve before there is a curve. Protect the vulnerable.
That is a big hit on the economy, but hopefully much cheaper than this one will be.
Another thought is to invest in pre-staged MASH units (fully supplied with medical equipment and supplies) that can be mobilized and staffed in 48 hours.
We could staff them with a reserve national volunteer medical brigade (ala National Guard) of Americans with various degrees of medical training -- doctors, nurses, lab techs, helper bees, support staff, etc. These folks would "drill" twice per year for 3-4 days a shot, and be paid for their drill sessions and time served when a pandemic hits. We could also give them tax breaks for their service and/or forgive student debt in stages (per years of service in the medical brigade). It would also provide a platform (like the military) that brings Americans together in service.